República Federativa do Brasil Ministério de Minas e Energia Companhia de Pesquisa de Recursos Minerais Diretoria de Geologia e Recursos Minerais Departamento de Recursos Minerais PROJETO PLATINA E ASSOCIADOS GEOLOGICAL, GEOCHEMICAL AND POTENTIALITY ASPECTS OF Ni-Cu-PGE DEPOSITS OF THE PARANÁ BASIN MAGMATISM Organization Sérgio José Romanini and Luiz Fernando Fontes de Albuquerque Superintendência Regional de Porto Alegre Abril 2001 TECHNICAL TEAM Luiz Fernando Fontes de Albuquerque PROJETO PLATINA E ASSOCIADOS Geology and Mineral Resources Manager Geól. Adalberto de Abreu Dias Sérgio José Romanini Geól. Andrea Sander Mineral Resources Supervisor Geól. Claudemir Severiano de Vasconcelos* Geól. Ídio Lopes Jr.* Luiz Antonio Chieregati Geól. Luiz Antonio Chieregati* Andrea Sander Geól. Luiz Fernando Fontes de Albuquerque Adalberto Dias Geól. Sérgio José Romanini Project Chiefs Geól. Valdomiro Alegri* * Superintendência Regional de São Paulo Luís Edmundo Giffoni Editing Geochemical Prospection Geól. Larry Hulbert* Geól. D. Conrod Grégorie* * Geological Survey of Canadá Typing Suzana Santos da Silva Digitizing/Illustration Giovani Milani Deiques English Version Arthur Schulz Junior Informe de Recursos Minerais Série Metais do Grupo da Platina e Associados, 29 Ficha Catalográfica R758 Romanini, Sérgio J.; org. Geological, geochemical and potentiality aspects of Ni-Cu-PGE de- posits of the Paraná Basin magmatism / Sérgio J. Romanini; Luiz Fer- nando F. Albuquerquer; orgs. - Porto Alegre : CPRM, 2001. 1 v. ; il - (Informe de Recursos Minerais - Série Metais do Grupo da Platina e Associados, n.º 29) 1. Projeto Platina e Associados I. Albuquerque, Luiz Fernando F.; org. II. Título III. Série CDU 553.491 (811.1) Presentation The Informe de Recursos Minerais is a publication that aims to ordem and divulge the results of the technical activities that CPRM carries out in the fields of economic geology, prospection, exploration and mineral economics. These data are issued as maps, papers and reports. According to the subject there are eight series of publications, named below. 1) Série Metais do Grupo da Platina e Associados; (Metals of the Platinum Group and Related Metals Series) 2) Série Mapas Temáticos do Ouro, Escala 1:250.000; (Thematic Maps for Gold – Scale 1:250.000 Series) 3) Série Ouro – Informes Gerais; (Gold – General Information Series) 4) Série Insumos Minerais para Agricultura; (Mineral Inputs for Agriculture Series) 5) Série Pedras Preciosas; (Precious Stones Series) 6) Série Economia Mineral; (Mineral Economy Series) 7) Série Oportunidades Minerais – Exame Atualizado de Projetos; (Mineral Opportunities – Up-Dated Review of Project Series) 8) Série Diversos (Sundry Series) Please contact directly the Superintendência Regional de Porto Alegre – SUREG-PA or the Divisão de Documentação Técnica – DIDOTE, in Rio de Janeiro to ask for copies of this issue, using the addresses listed inp the back cover. 1 - Foreword CPRM National PGE project start- these bodies were studied by Dias (1992- up and its activities were grounded on the 93), Chieregati (1995) and Sander (1993 – Brazilian territory high potential regarding 94a, 94b and 95), Romanini and Albuquer- platinum group metals and Ni-Cu sulphides que (1996), Alegri and Vasconcelos (1997) ore deposits. M. Farina, l988, through and Hulbert and Gregory (1999). The pre- quantitative gitology principles enlighted the sent report is based on these studies and geological environments favorable to min- is, in part, a compilation. So, this is an inte- eralization, among them the Paraná Basin gration document of a part of significance of magmatism. the present knowledge, encompassing regional geological context and detailed This magmatism was considered intrusions investigations in regard to their similar to the Siberian Platform mineral geochemical aspects, also including the fields of Noril’sk and Talnakh and those of volcanic rocks and some Paleozoic sedi- the Karoo Province, South Africa. The first ments. Analytical results of all samples ones are Ni-Cu producers - 6% and 46% of made by the Geological Survey of Canada world production, respectively – and their are also included. total reserves are 8% of known ones (US Geol. Survey, Min. Comm. Summaries, Annex, there are tables showing Jan. 1999). USGS also inform that mineral geographic location of analyzed intrusive consumption between the years 1994 and and sedimentary samples, due to the fact l998 was increasing and the cumulative that it is unpractical to put this situation into growth was 46% regarding Pt and 57% to a single map. Pd. Prices show the same trend with an important growth in the 1999/2000 years Among the results of geochemical (Gazeta Mercantil). prospecting of stream sediments and heavy minerals presented by Chieregati (1995), Aiming to a preliminary evaluation only the Franca’s sill chromite and chal- of PGE metal potential of Paraná Basin copyrite grains are considered. As it seems, magmatism and taking into account the other results of this exploration are unim- favorable economic world consumption, a portant because of a general depletion of number of intrusions – dykes, sills and chalcophyles of these sill rocks. Negative complexes – were listed and investigated. results were achieved in other services Geological and geochemical aspects of done afterwards. 1 2 - Methodology The following methodology was pyrohydrolysis with a detection limit of 50 adapted: target areas selection using tradi- ppm. tional literature models for similar geological environments, field reconnaissance, drill ICP-MS was used for REE with a profiles studies, rock sampling and chemi- detection limit of 0.1 ppm for Ce, La and cal and petrographycal analysis. Field Nd, 0.05 ppm for Yb and 0.02 for the oth- teams were updated regarding new tech- ers. IGP-MS limits are: for Cs, Ti, U and Th nologies and Drs. R. Eckstrand and L. Hul- : 0.02 ppm; Hf, In, Nb and Rb: 0.05 ppm; bert (GSC) worked as technical advisors. Ag and Ga: 0.1 ppm; Cd, Mo and Ta: 0.2 ppm; Bi, Sn and Zn: 0.5 ppm and Pb: 2 Surface rock sampling focused into ppm. ICP-ES determinations included: Co, sills, dykes and hypabyssal mafic bodies as V and Zn with a limit of 5ppm; Cr, Cu and well as core samples of previous explora- Ni with 10 ppm and Ba, 20 ppm. tion services of sills intercalated into sedi- mentary sequence. Biggest and the most Intrusive rock elements Pt, Pd and textural/compositional variegated mafic Au were analyzed by means of ICP ultra- bodies were selected to be sampled. sonic nebulizer after a tablet fire assay concentration of 30 g of samples, in Pb Paleozoic country rock sediments tablets in the ACME Analytical Labs, Van- were also sampled for comparison pur- couver. This method has a 0.5 ppb limit for poses. Pb and Pt and 1ppb for Au. For 0.1 and 0.01 ppb for Pt and Pd respectively, ICP- Sill samplings were done accord- MS was also used. ingly to textural and compositions changes. Dykes were sampled at their border, inter- Drs. L.S. Marques (Instituto Agro- mediate and central positions. nomico e Geofisico – USP) and D.W. Peate (Dept. of Earth Sciences, The Open Uni- Samples Selection and Analytical Pro- versity, England) provided samples of vol- cedures canic suites for analyses at GSC for addi- tional elements. References on these sam- Geochemical investigations were ples and regarding geochemical back- conducted for 302 samples, among them ground are in Peate and Hawkesworth 225 of intrusive rocks, 63 of basaltic flows (1986), Piccirilo et al (1988), Bellieni et al and 14 of country sedimentary rocks. (1984) and Mantovani et al (1985). Major elements, trace elements and All analytical data were recalculated REE analyses were done at GSC labs in in an anhydric base and Fe2O3/FeO ratio (1) Otawa. SiO2, TiO2, Al2O3, Fe2O3t, MnO, was turned equal to 0.15 before Mg# and MgO, CaO, Na2O, K2O and P2O5 are de- other parameter calculations. termined by means of X-ray fluorescence with an 1% error regarding concentration. Table A, following, shows groups of H2Ot, FeO, CO2, C and fire assay were samples and their specimen numbers done by means of traditional chemical (quantity): methods. S, F and Cl were analyzed by 2 Série Metais do Grupo da Platina e Associados, 29 INTRUSIVE BODIES,VOLCANIC SUITES AND SED. ROCKS SAMPL. QTY Porto Alegre Metropolitan Region and Irui-Leão Area Intrusive Bodies (PA) 29 Lomba Grande Basic Complex (LG) 03 Maracajá-Barro Branco Basic Body- core samples (MB) 26 Maracajá-Barro Branco Basic Body – surface samples (MBB) 32 Rio Urussanga Basic Body (RU) 16 Pouso Redondo-Rio do Campo Basic Body (PRR) 40 Ponta Grossa Arch Dykes (PGA-D) 25 Ponta Grossa Arch Sills (PGA) 54 High Ti Basic Volcanic Suite (HTV-B) 19 High Ti Intermediate Volcanic Suite (HTV-I) 04 Low Ti Basic Volcanic Suite (LTV-B) 23 Low Ti Intermediate Volcanic Suite (LTV-I) 11 Low Ti Acidic Volcanic Suite (LTV-A) 06 Sedimentary Rocks (SD) 14 Table A – List of sampled rocks and their number of specimens (1) Mg# = Mg/Mg + Fe 3 3 - Stratigraphy and Magmatism 3.1 Generalities sented in Irati Formation, basin’s North third portion. There are also evaporites and bi- Paraná Basin is an intracratonic tuminous mudstone horizons into this for- basin, located at South-American Platform, mation. Another must into this basin are covering an area of 1,200,000 km2, about coal deposits of Rio Bonito Formation, in 1,000,000 km2 in the Brazilian territory. the states of Santa Catarina and Rio Some authors consider Chaco-Paraná Basin, Grande do Sul. located at Argentinean territory, as an inte- grating part of Paraná Basin, increasing its In the tectonic and stratigraphic area to more than 1,600,000 km2 (Figure 01). evolution of the Paraná Basin four stages were identified (Melfi et al, 1988). The first Paraná Basin development came one corresponds to the deposition of the since Medium-Low Palaeozoic until the end marine sediments of the Paraná Group of Mesozoic, building more than 4,000 me- (Devonian – Lower Carboniferous) that was ters of sediments, plus 1,700 meters of lava preceded by the imposition of the Ponta flows (Almeida, 1981; Zalan et al,1986).